Headroom Amps V Speakers

[geoffers 0]

Hi all,

 

I have read a few threads on this site which say that some head room is advisable (larger amp than speakers) .Last night my main (newer amp and larger) let me down :damn: . Towards the end of gig, the left hand channel started clipping even when turned very low, so I turned the amp off. Fortunately, I use two amps and four speakers, so was able to complete the gig, surprisingly without any one noticing. My back up set of speakers are only 150 w each but have a good sound ( although heavy to carry !)

 

I have decided to get a new amp and bin this one despite it only being 18 months old, I had it repaired in January because of problem with the fan ! (I will check this is not same problem as the new fan is under warranty)

 

I need to get a new amp quickly as I have gig next weekend and would prefer not go with one amp and one set of speakers. The speakers I will be using with my new amp are 300w 8ohms. I have seen a 800w amp in my budget range, does this give me enough headroom ?

 

Please advise

 

:thanks:

 

Geoffers

[DJ Marky Marc 0]

More details on the make and models are needed before someone can realy help...

 

is that 800w total power bridged or 800 per side at 8ohms.

 

if yor speakers are 300w RMS then you need something between 300 and 600 watts per side at 8 ohms....

 

 

[Andy Westcott 0]

Just a point which needs to be made, although I've made it before:

 

Be aware that this idea of the need to have an amp rated higher than the speakers is a fallacy, and a recipe for burning smells if you run near full output.

 

I'm unsure quite where this old wives' tale originated, but probably due to the need to get the most use out of a set of speakers, on the understanding that if the speakers have extra unused capacity, that represents money wasted.

 

And having an amp rated lower than the speakers will not damage them - quite the opposite - you will in fact find it difficult, if not impossible, to damage them at all.

 

No doubt someone will disagree, but it really is a simple matter of power dissipation, something any electronics engineer will understand, and not rocket science.

 

Ultimately it all depends on how loud you play your music, and how close to the amp's limit you find yourself operating. If you run a 300 watt amp and never find the need to clip it, you will probably be OK with 200 watt speakers, having your skin saved by the fact that music is not a continuous noise, but comes in pulses, or beats if you like, which average out at a rather lower figure than the maximum.

 

If, however, you tend to see the clip light regularly, or play with the VU touching the red, then you really want to have speakers rated equal to, or even above, the amp's rating to ensure ultimate reliability.

[DJ Marky Marc 0]

here we go again...

 

there are many reasons why a small amp is worse than a amp that's rated more than the RMS of the speakers..

 

and the people who make the speakers would not recommend amps rated twice the RMS if they were not sure or had not done the math..

 

a small amp will rreach the point of clipping well before the speakers get to the max output..

 

amp clipping is evil,, it cooks speakers..

 

so get a bigger amp and never get to the point of clipping..

 

[Norfolk DJ 0]

 

Price differentials between say a 600 watt and 1000 watt amp are very small now in the medium end of the market. I would buy the lagest within my budget.

 

Sometimes better value getting an amp and speakers package if you want to continue with a passive set up.

[TonyB 0]

I agree with Andy and to explain the myths a bit further, there is an article at http://billfitzmaurice.com/phpBB2/viewtopic.php?t=1886 that goes into more detail smile icon

[DJ Marky Marc 0]

well when it sounds rubbish or goes wrong don't say I didn't tell you so...

 

[Andy Westcott 0]

Remember guys, to keep this discussion light-hearted. smile icon

Hardly something to go to war over.

 

Anyhow, thanks TonyB for placing that link there - it might go some way towards dispelling this rather silly myth, on this forum at least.

 

To quote a line from that site:

"There are only two ways that a speaker can be damaged, both of which occur from too much input power."

 

Absolutely correct. It happens either by pulling the speaker to bits, or by overheating it.

You will never, ever burn out a 600 watt RMS driver with a 200 watt RMS amp, even if you were to clamp the diaphram solid to present the minimum impedance.

 

If you are looking for long term reliability, as well as good sound quality, you must avoid overdriving the poor ol' speaker; Not only will it shorten its life, but you will get distortion products as a result of the driver being driven beyond its X-Max, in other words into the non-linear portion of its excurtion.

 

Manufacturers will advertise that a certain speaker can be powered by a higher rated amp, but as always this is just a numbers game put on for the customer, hoping to impress with an apparently higher rating, but keeping their fingers crossed that the speaker is not actually damaged. The few that are, are taken as an acceptable returns loss, and allowed for in the pricing.

 

And I will argue this point until the cows come home. tongue out icon

[geoffers 0]

Thanks for all the advise.

 

Geoffers